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SLEEP(1) FreeBSD General Commands Manual SLEEP(1)
NAMEsleep -- suspend execution for an interval of time
SYNOPSISsleepsecondsDESCRIPTION
The sleep command suspends execution for a minimum of seconds.
If the sleep command receives a signal, it takes the standard action.
When the SIGINFO signal is received, the estimate of the amount of sec-
onds left to sleep is printed on the standard output.
IMPLEMENTATION NOTES
The SIGALRM signal is not handled specially by this implementation.
The sleep command allows and honors a non-integer number of seconds to
sleep in any form acceptable by strtod(3). This is a non-portable exten-
sion, and its use will nearly guarantee that a shell script will not exe-
cute properly on another system.
EXIT STATUS
The sleep utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
To schedule the execution of a command for x number seconds later (with
csh(1)):
(sleep 1800; sh command_file >& errors)&
This incantation would wait a half hour before running the script com-
mand_file. (See the at(1) utility.)
To reiteratively run a command (with the csh(1)):
while (1)
if (! -r zzz.rawdata) then
sleep 300
else
foreach i (`ls *.rawdata`)
sleep 70
awk -f collapse_data $i >> results
end
break
endif
end
The scenario for a script such as this might be: a program currently run-
ning is taking longer than expected to process a series of files, and it
would be nice to have another program start processing the files created
by the first program as soon as it is finished (when zzz.rawdata is cre-
ated). The script checks every five minutes for the file zzz.rawdata,
when the file is found, then another portion processing is done courte-
ously by sleeping for 70 seconds in between each awk job.
SEE ALSOnanosleep(2), sleep(3)STANDARDS
The sleep command is expected to be IEEE Std 1003.2 (``POSIX.2'') compat-
ible.
HISTORY
A sleep command appeared in Version 4 AT&T UNIX.
FreeBSD 10.1 April 18, 1994 FreeBSD 10.1